The present invention relates to a fragrance carrier and delivery system formed of mixtures of water miscible and immiscible polymers or oligomers able to form a surfactant complex gel dispersion capable of yielding high levels of fragrance deposition onto the skin, hair or other surfaces such as tiles or textiles, from a cleansing consumer product comprising a mixture of surfactants. The internal and external phases, or dispersible and dispersing phases, of this surfactant complex gel dispersion are formed when a mixture of various polymers, oligomers and optionally stabilizers are combined with a surfactant cleansing system to form an association surfactant complex structure with a polymer to polymer ratio, (polymer/oligomer/stabilizer mixture) to surfactant ratio, and composition that are selected so as to dissolve fragrance raw materials having a wide range of solubilities and volatilities.
Fragrance enhanced deposition and long lastingness are two benefits commonly searched for when formulating body or hair washes, liquid soaps, detergents and softeners, intended to be applied on the skin, hair, textile or other surfaces, all these products containing cleansing or conditioning surfactants or surface active agents. The amount of fragrance deposition on said surfaces, and its longlastingness, are however limited because most fragrances are solubilized in the free surfactant micelles and washed off by the cleansing or conditioning surfactant system present in these types of consumer products.
Fragrances are typically oily substances that, when added to a surfactant-containing composition, become solubilized in the surfactant micelles by partitioning. This process limits the amount of fragrance deposition on the surface treated with the composition, firstly, because the fragrance is greatly diluted in the micelles, and, secondly, because the small amount of fragrance that is deposited upon micelle breakage is re-solubilized back into the surfactant system.
Attempts to solve this problem have led to the use of cationic polymers, alone or in combination with fragrance carriers, in the surfactant solution. Fragrance deposition by these systems onto the surface, in particular the skin, is mainly attained by the use of either a cationic surfactant or a cationic polymer. Typical prior art in this field is represented for example by U.S. Pat. Nos. 5,804,538, 5,843,875 and 5,891,833. These documents all describe the use of cationic polymers to assist in enhanced fragrance deposition from body washes onto the skin.
Fragrance carriers used in the prior art typically consist of either a cationic polymer alone, that forms ion pairs with the surfactant, or a cationic polymer combined with oily liquid droplets in which the fragrance is dissolved, or combined with hydrophobic solid waxes or polymeric solid particles in which the fragrance is encapsulated.
The main drawbacks of using a cationic polymer forming ion pairs with a surfactant is that the level of fragrance binding is extremely low and therefore these carrier systems do not show a high level of fragrance deposition on the treated surface.
Drawbacks presented by carrier systems that resort to the use of cationic polymers in combination with oily liquid droplets are, first, that the oil in itself is partially solubilized in the surfactant micelles, and second, that the fragrances gradually diffuse out of the oil droplets by partitioning into the micelles when the cleansing composition reaches thermodynamic equilibrium. These two processes reduce significantly the level of fragrance deposition onto the surface on which the product is applied. A typical example of this type of solution is the fragrance delivery system described in US patent application 2002/0055452.
Hydrophobic waxes and polymeric solid particles, although not solubilized by the surfactant micelles because of their solid character, still lose fragrance by partitioning into the micelles. Furthermore, solid particles are difficult to deposit onto the skin, hair and other surfaces, since they do not break during shear, and in addition they are easily removed during washing.
U.S. Pat. No. 6,491,902 and European patent application 1 146 057 are pertinent examples of prior art describing the use of solid polymeric particles as fragrance carriers.
Encapsulation of fragrances in hollow spheres, nanosomes, liposomes, microspheres, etc., present similar challenges. In most cases, the solid walls of these spheres are unstable at high surfactant concentrations and they are also permeable, allowing the gradual partitioning of fragrances into the surfactant micelles.
In summary, the main problems posed by these prior known techniques are: first, that they lose fragrance into the surfactant micelles by partitioning, second, that, when the hydrophobic vehicle is a triglyceride or mineral oil, it can be solubilized into the micelles, and third, that when the vehicle is a solid particle, or has solid walls, it cannot be broken by shear, thus preventing fragrance deposition, and that it also allows the gradual diffusion of fragrances into the micelles.
In more recent documents such as US 2004/0087476 and 2004/0091445, there is described the use of cationic polymeric particles which are preferably not admixed with the fragrance prior to addition thereof to the end product containing the surfactant. The cationic polymers in question must have affinity to specific perfumery raw materials having defined characteristics. In addition, the fragrance polymeric systems there-described must obey certain parameters which are not generally defined or current in the art, but are defined only in the above-mentioned documents. In other words, the described resulting fragrance carriers or polymeric fragrance particles are quite specific and relate only to specific cationic polymers and fragrance raw materials, as mentioned in the examples. The drawback of this type of system is the danger that the skilled perfumer may be limited in his activity and choice of perfumery materials by having to formulate fragrances mainly as a function of the carrier polymer available, rather than on the basis of his hedonic objectives.
In fact, in the art of perfumery and more particularly of fragrance delivery and deposition on substrates treated with perfumed, surfactant-containing, consumer products, it is highly desirable to be able to deal with fragrance carrier systems that are as universal as possible, i.e. that can be easily adapted to the general characteristics of the end consumer product with which the surface or substrate is treated, without overly restricting the palette of materials that the perfumer has at his disposal for creating pleasant, original and effective fragrances meeting consumer preferences. The present invention addresses precisely this problem and also obviates the other problems encountered in the prior art of reference.
We have now surprisingly been able to establish that a more general solution to the prior art problems above-mentioned is that of providing a fragrance carrier system that takes into account the composition of the end product base, in particular the nature of the essential component in skin, hair, textile and other surface cleaners and conditioners, i.e. the surface active agent or surfactant system.
The present invention thus provides a fragrance carrier and delivery system which essentially consists of a gel complex resulting from the interaction of the fragrance carrier/deposition polymer combination with the surfactant molecules contained in the end product. The fragrance carrier/deposition combination comprises various types of water miscible and immiscible polymers, oligomers, and optionally stabilizers, able to form association complexes with the surfactant molecules at any dilution, when combined with the cleansing/conditioning surfactant platform.
We have now been able to establish that surfactant complex gel structures produced by combination of carefully selected mixtures of water miscible and immiscible polymers and/or oligomers optionally stabilized, with cleansing surfactant systems in particular, enable the formation of higly substantive gels which preferentially dissolve the fragrance and allow its effective deposition on the surfaces being cleansed. The external dispersing phase of such gel-liquid polymer/polymer dispersions (hereinafter referred to as “GLPPD”), which are one object of the invention, consists of a water miscible cationic polymer, or a mixture of water-miscible cationic polymers, able to form an aqueous surfactant complex gel when combined with a detergent surfactant system, whereas the internal dispersible phase of the GLPPD consists of one or more water immiscible liquid polymers or oligomers, and optionally stabilizers, also able to form complexes with a cleansing surfactant. The GLPPD can be made in situ in the surfactant base or be prepared separately and then added to the surfactant base. The fragrance, which can be of any appropriate composition, can also be admixed with the GLPPD, separately from the surfactant base, or be added after the complex gel has been formed in the surfactant base.